3 research outputs found
A review of model based and data driven methods targeting hardware systems diagnostics
System health diagnosis serves as an underpinning enabler for enhanced safety and optimized maintenance tasks in complex assets. In the past four decades, a wide-range of diagnostic methods have been proposed, focusing either on system or component level. Currently, one of the most quickly emerging concepts within the diagnostic community is system level diagnostics. This approach targets in accurately detecting faults and suggesting to the maintainers a component to be replaced in order to restore the system to a healthy state. System level diagnostics is of great value to complex systems whose downtime due to faults is expensive. This paper aims to provide a comprehensive review of the most recent diagnostics approaches applied to hardware systems. The main objective of this paper is to introduce the concept of system level diagnostics and review and evaluate the collated approaches. In order to achieve this, a comprehensive review of the most recent diagnostic methods implemented for hardware systems or components is conducted, highlighting merits and shortfalls
System diagnosis for an auxiliary power unit
Even though the Auxiliary Power Unit (APU) is a widely used system in modern
aviation, the existing experimental, simulation and diagnostic studies for this
system are very limited. The topic of this project is the System Diagnosis of an
APU, and the case study that is used in this research is a Boeing 747 APU.
This APU was used to develop an experimental rig in order to collect performance
data under a wide range of loading and environmental conditions. The
development of the experimental rig consumed considerable time and required
the design and installation of structures and parts related with the control of the
APU, the adjustment of the electric and pneumatic load and the data acquisition.
The validation of the rig was achieved by a repeatability test, which ensures that
the collected measurements are repeatable under the same boundary conditions,
and by a consistency test, which ensures that the performance parameters are
consistent with the imposed ambient conditions. The experimental data that are
extracted from the rig were used to calibrate a physics-based (0-D) model for
steady-state conditions.
Data that correspond to faulty conditions were generated by injecting faults in the
simulation model. Based on the most prominent APU faults, as reported by The
Boeing Company, six components that belong to different sub-systems were
considered in the diagnostic analysis, and for each one of them, a single fault
mode was simulated. By using healthy and faulty simulation data, for each
component under examination, a classification algorithm that can recognise the
healthy and faulty state of the component is trained. A critical part of the
diagnostic analysis is that each classifier was trained to recognise the healthy
and the faulty state of the corresponding component, while other components can
be either healthy or faulty. The test results showed that the proposed technique
is able to diagnose both single and multiple faults, even though in many cases
different component faults resulted in similar fault patterns.Transport System